3d catheter-based ultrasound assembly with gimbal-mount transducer and single-coil drive

ABSTRACT

Described are embodiments of devices and methods for imaging a body conduit, such as a blood vessel. In particular embodiments, the catheter has a chamber within which is a transducer mounted to a pivot mechanism. A coil provides a pivot force to the transducer. A magnet is attached to the transducer and is receptive of a torque applied by a magnetic field produced by energizing of the coil. A driving mechanism receives an impact from the pivot member and causes the pivot mechanism to rotate about a rotation axis.

REFERENCE TO RELATED APPLICATION

This application is a continuation of PCT/US2014/013850, filed Jan. 30,2014, which claims the benefit of U.S. Provisional Patent ApplicationNo. 61/758,936, filed Jan. 31, 2013, which is hereby incorporated byreference in its entirety.

FIELD OF THE DISCLOSURE

The present disclosure concerns devices and methods for ultrasound usewithin the human body, including devices and methods for employingultrasound to image body areas, such as the interior of blood vessels.

BACKGROUND

Ultrasound technology has been used for therapeutic and diagnosticmedical procedures, which can include providing imaging of internalportions of a body. For example, devices have been proposed for usingultrasound imaging within blood vessels to view the condition of thevessel and/or placement or condition of a device placed in the vessel.However, a number of problems with such devices remain. For example,many such devices provide at best an image of a cross section of tissueor other items of interest, i.e. a thin, disk-shaped slice of theinterior of a blood vessel with a portion in the center that is notwithin the range of the ultrasound beam. In some other devices, theultrasound beam is directed at a fixed angle that is not substantiallyperpendicular to the longitudinal axis (e.g. at 45 degrees). In thiscase the imaged region is static in the form of a portion of the surfaceof a cone, also with a center portion that is not within the range ofthe ultrasound beam. In either case, in order to visualize the entiretyof a significant length within the body (e.g. surfaces or portions oftissue, or of devices), the device must be moved along that length, withrespective images of cross sections at particular locations taken. Suchmovement may be inexact, and may include risks associated with blindinsertion of the device through the vessel. It is also slow. Typicalpull back images take on the order of 30 s to perform (at a speed ofabout 0.1 mm/s). Additionally, any changes in the orientation of thetransducer during pullback distort the image.

Three-dimensional information provides the added value that it can beused to help in navigation of devices within the vasculature andconfirmation of position of the devices. In an intravascular example,catheters can be moved up and down vessels and the image data obtainedvia ultrasound can be combined or otherwise processed in order to createthree-dimensional information. However, the catheter tip motion andangle must be known in order to produce accurate and usable data.Three-dimensional images may be acquired by one-dimensional arraysconnected to a mechanical actuator, to move the arrays within thecatheter or other device. Such designs are expensive and generallyrequire more space in a device than many vessels will permit. To achievegood image quality, such array transducers must simultaneously transmitand receive on many separate channels. That condition requires severalexpensive and bulky coaxial cables. Fewer coaxial cables can be used,but doing so reduces the quality of the image and image frame rate.

Ultrasound devices have been proposed which include a motion of atransducer about two axes to provide three-dimensional information.However, the mechanical mechanisms that provide such movement tend to bebulky and require dimensions which are unsuitable for applications insmall body areas. Additionally, the problem of providing motion to atransducer must be solved. Designs including torque cables can beproblematic. Practically, a sufficiently maneuverable torque cablecreates a potential for delay in the transferring of torque from one endof the cable to the other, as the cable stores and releases elasticenergy, which causes the transducer assembly to rotate at a non-uniformrate even when the rotation source rotates at a uniform rate. Thenon-uniform rotation rate causes the resulting data or images to bedistorted. These problems are magnified if two torque cables are usedfor two-axis movement of the transducer. In some cases, separate motorscan be used to provide movement to the transducer. However, motorsrequire additional space and can include further disadvantages such ascontrol wires or structural components which cross the viewing windowand cause a portion of an image to be blocked. Additionally, existingfeedback mechanisms for controlling complex motor motion can be costlyand bulky.

There remains a need for accurate and efficient application ofultrasound in three dimensions along a substantial length of a smallbody area, for example to provide a physician with a real-time viewalong that length. There also remains a need for devices that can view amedical device and one or more tissues or tissue parts simultaneously,particularly in cases in which the device and tissue(s) could not havebeen imaged reliably in any two-dimensional plane.

SUMMARY

Among other things, disclosed are apparatus and methods for providing anultrasound beam with two controllable degrees of freedom within the bodyof a patient. For example, such apparatuses can include a transducer fortransmitting and/or receiving ultrasound signals and a pivot mechanismwhich is rotatable about a rotation axis. A pivot member is mounted tothe pivot mechanism and pivotable about a pivot axis that issubstantially perpendicular to the rotation axis. Also included is adriving mechanism positioned within the pivot path of the pivot membersuch that during rotation about the pivot axis a portion of the pivotmember strikes the driving mechanism and causes the pivot mechanism torotate about the rotation axis.

The medical device can include a coil positioned concentric to and alongthe rotation axis. The pivot member can include a magnetic layer and thetransducer. The coil includes a plurality of electrically conductivewindings, such that application of electric current to the coil createsa torque on the pivot member about the pivot axis. The pivot member canreciprocate alternatively between a driving pivot stroke and anon-driving pivot stroke such that driving pivot stroke causes the pivotmechanism to rotate about the rotation axis and the non-driving pivotstroke does not cause the pivot mechanism to rotate about the rotationaxis. The electric current can be an alternating current. The drivingpivot stroke has a torque which is larger than the torque of thenon-driving pivot stroke. The electric current can include a directcurrent offset component to produce a difference in the torque betweenthe driving pivot stroke and the non-driving pivot stroke.

The medical device can include an engagement surface positionedcylindrically and concentric to the rotation axis. The driving mechanismis positioned to engage the pivot member and engagement surface. Thepivot member is pivotable through a range bounded by the drivingmechanism. During pivotal rotation of the pivot member, abutment of thepivot member against the driving mechanism moves the driving mechanismto engage the engagement surface. Engagement of the driving mechanismwith the engagement surface causes the pivot mechanism to rotate aboutthe rotation axis. The medical device can include a stop bar and adriving rod fixed relative to the stop bar. Stop bar has a portionposition within the pivot path of the pivot member and the driving rodis positioned to engage the engagement surface when the pivot memberstrikes the stop bar. Alternatively, the medical device can include astop bar rotationally mounted about the rotation axis and a driving rodconnected to the stop bar. The stop bar has a portion positioned withinthe pivot path of the pivot member which is offset from the rotationaxis and a driving rod is positioned to engage the engagement surfacewhen the pivot member strikes the stop bar.

The medical device can include a ring gear positioned cylindrically andconcentric to the rotation axis. The driving mechanism can include astop bar with a toothed edge positioned to engage the ring gear. Thedriving mechanism is positioned to engage the pivot member and ringgear. The pivot member is pivotable through a range bounded by the stopbar such that during pivotal rotation of the pivot member, abutment ofthe pivot member against stop bar causes the toothed edge to move alongthe ring gear.

The medical device can include a diametric permanent magnet having afirst magnetic field with poles aligned substantially perpendicular tothe pivot axis. Application of electric current to the coil creates asecond magnetic field with poles aligned substantially along therotation axis such that interaction between the first and secondmagnetic fields creates the torque.

The medical device can include a bias member. The pivot member caninclude the transducer. The bias member can be positioned to apply abias member force to the transducer which biases the transducer to aneutral position about the pivot axis and relative to the pivotmechanism. The torque is dependent upon the electric current to the coilsuch that when the torque is insufficient to overcome the bias memberforce, the bias member force returns the transducer to the neutralposition. The bias member can be a conductor configured for carryingsignals from the transducer.

The transducer is movable throughout a range which defines a viewingwindow extending from the transducer. The medical device can include anopaque feature positioned within the viewing window such that the opaquefeature provides angular positional information about the pivot member.

The medical device can include a tubular member for housing thetransducer, driving mechanism, and pivot mechanism. The tubular memberhas a distal chamber defined at least in part by a wall portion of thetubular member. The distal chamber houses at least the transducer andthe medium. The wall portion and the medium have similar acousticimpedance to the part of the body into which the tubular member isinserted so that reflection of ultrasound at the boundary of the mediumand the wall portion and at the boundary of the wall portion and thebody environment is reduced to a level acceptable for imaging throughthe boundary. The tubular member can be a catheter.

The medical device can include a transducer for transmitting and/orreceiving ultrasound signals, and a pivot mechanism rotatably mountedabout the rotation axis. Also included is a pivot member pivotallymounted to the pivot mechanism about a pivot axis substantiallyperpendicular to the rotation axis. An engagement surface is positionedcylindrically and concentric to the rotation axis. A driving mechanismis positioned to engage the pivot member and engagement surface. Thepivot member is pivotable through a range bounded by the drivingmechanism such that during pivotal rotation of the pivot member,abutment of the pivot member against the driving mechanism moves thedriving mechanism to engage the engagement surface to create areactionary force which causes the pivot mechanism to rotate about therotation axis. The pivot member can include a magnetic layer and thetransducer. A coil can be positioned concentric to and along therotation axis. The coil can include a plurality of electricallyconductive windings such that application of electric current to thecoil creates a torque on the pivot member about the pivot axis.

The medical device can include one or more sensors for sensing theposition and/or movement of the transducer, and/or a portion supportingor coupled to the transducer (e.g., the pivot mechanism, pivot member,or magnetic layer), about the pivot axis and/or the rotation axis. Adata processing system can use the sensor data to calculate the speedand/or position of the transducer and correlate that sensor data withthe data or signals received by the transducer so as to generate agraphic display (e.g., an IVUS image). The same or a different dataprocessing system can also use the sensor data in controlling thevoltage applied to the coil. For example, a feedback loop can increaseor decrease the voltage of coil so as to adjust the speed at which thepivot member and transducer pivot.

Further forms, objects, features, aspects, benefits, advantages, andembodiments of the concepts will become apparent from a detaileddescription and drawings provided herewith.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustrative side view of a medical device showing a pivotmechanism.

FIG. 2 is an illustrative partial perspective view of the pivotmechanism of FIG. 1.

FIG. 3 is an illustrative top cross-sectional view of the pivotmechanism of FIG. 1 showing a driving mechanism.

FIG. 4 is an illustrative partial side view of a pivoting transducerillustrating operation in conjunction with a drive signal.

FIG. 5 is an illustrative partial side view of a pivoting transducerillustrating operation in conjunction with a drive signal having a DCoffset component.

FIG. 6 is an illustrative partial side view of a pivoting transducerillustrating operation in conjunction with a drive signal having a DCoffset component opposite to that shown in FIG. 5.

FIG. 7 is an illustrative top cross-sectional view of the pivotmechanism of FIG. 1 showing an alternative driving mechanism.

FIG. 8 is an illustrative top cross-sectional view of the pivotmechanism of FIG. 1 showing an alternative driving mechanism.

FIG. 9 is an illustrative partial perspective view of the pivotmechanism of FIG. 1 showing an alternative driving mechanism.

DESCRIPTION OF THE SELECTED EMBODIMENTS

For the purpose of promoting an understanding of the principles of thedisclosure, reference will now be made to the embodiments illustrated inthe drawings and specific language will be used to describe the same. Itwill nevertheless be understood that no limitation of the scope of theclaims is thereby intended. Any alterations and further modifications inthe described embodiments, and any further applications of theprinciples of the disclosure as described herein are contemplated aswould normally occur to one skilled in the art to which the disclosurerelates. One or more embodiments are shown and described in detail,although it will be apparent to those skilled in the relevant art thatsome features that are less relevant may not be shown for the sake ofclarity.

Referring now generally to the drawings, there are shown exemplaryembodiments of a device 20 for internal ultrasound procedures. Suchdevices may be diagnostic or therapeutic (including interventional) inapplication, and include devices inserted percutaneously, subcutaneouslyor endoluminally into the patient. Device 20 can be used with a systemwhich includes a console (not shown) for processing data or signalsreceived from an ultrasound transducer. The ultrasound console can be atype which is generally used for medical ultrasonic imaging, e.g.generally including control devices usable by a physician and a graphicdisplay which displays graphical images obtained during an ultrasoundprocedure. Device 20 can be used for obtaining images at variouslocations of a body such as a blood vessel, urethra, ureter, vagina,rectum, throat, ear, or through an artificial tract (or lumen) bypercutaneous puncture for example. The console portion can be connectedto commercially-available ultrasound probes or catheters with compatiblepinout, or other medical devices which are configured for endoluminalprocedures. Device 20 is capable of transmitting and receivingultrasound signals and then communicating data obtained from ultrasoundsignals to the console.

In the embodiment shown schematically in FIG. 1, device 20 includes acatheter 22 or other flexible elongated or tubular member having a wall24 defining an internal chamber 26, within which is included atransducer 28, a pivot mechanism 30, a driving mechanism 32, and a coil80. Catheter 22 is sized and configured for insertion into and/or travelalong bodily orifices or lumens. As will be discussed further below,pivot mechanism 30 allows transducer 28 to be turned around a rotationaxis (axis A) of device 20 as well as pivoted around a pivot axissubstantially perpendicular to the rotation axis, allowing the directionof ultrasound emission and reception to extend forward (axially relativeto the rotation axis) and laterally (radially relative to the rotationaxis). In the illustrated embodiments, the rotation axis is thelongitudinal axis (i.e. extending axially through catheter 22) of device20, and the pivot axis is a lateral axis (e.g. perpendicular to thelongitudinal axis). Transducer 28 in conjunction with driving mechanism32 and pivot mechanism 30 is capable of transmitting and receivingultrasound signals in a variety of directions or orientations which arepassed along data signal communication lines between transducer 28 andthe ultrasound console.

Catheter 22 in the illustrated embodiment is an elongated device ofplastic or other sturdy flexible material. Catheter 22 includes acontrol end which during use is nearest to the user and an applicationend which during use is nearest to the user's point of interest. Theterms “control” and “application” are used throughout this descriptionto describe these positional orientations. Wall 24 surrounds chamber 26,which is at or near the application end of device 20 in the illustratedembodiment. The control end of wall 24 and/or catheter 22 may extendoutside of the patient during use, or may attach to another piece thatextends outside the patient, and may end in a handle or other operatingportion for maneuvering catheter 22.

Catheter 22 has at least a portion that presents a minimal barrier tothe passage of ultrasound signals so that ultrasound images ofsurrounding matter (e.g. tissue(s) or implant(s)) may be reasonablyacquired through the barrier. Catheter 22 has a portion surroundingdevice 20 that is constructed of a material which is substantiallyecholucent (i.e. having small ultrasound attenuation, or having a smalldifference in acoustic impedance with the surrounding environment) whenplaced in the surrounding working environment, such that it acts as anacoustic window which allows passage of ultrasound signals with minimalreflection. It will be understood that only the application end ofcatheter 22 (e.g. wall 24) need be acoustically transparent, but more orall of catheter 22 may be made of the same material as wall 24 in someembodiments. For example, when used within a blood vessel containingbody tissues and blood, it is preferable for catheter 22 to beconstructed of a material which is structurally rigid and which hasacoustic impedance similar to that of body fluids such as blood.Possible materials could include, for example, a polymer material suchas high density polyethelene, polymethylpentene (PMP), or acrylonitrilebutadiene styrene (ABS). It has been determined that in some cases thethickness of at least the portion of catheter 22 which serves as theviewing window can be approximately N/2 (where N is a positive integer)of the wavelength corresponding to the center frequency of theultrasound signal.

Particular embodiments of catheter 22 or at least chamber 26 arecylindrical, and are sized for insertion into and passage through bodyconduits, such as insertion into the femoral artery and passage throughit toward the heart. Wall 24 may have a port or other feature to allowinjection of fluid (e.g. saline, oils, or alcohols) into chamber 26 togive chamber 26 ultrasound characteristics similar or substantiallyidentical to that of wall 24 and the surrounding bodily environment(e.g. the blood stream). A sealing member 36 can be placed on thecontrol side of pivot mechanism 30 and transducer 28 or the portion ofchamber 26 containing transducer 28 and a fluid, in the illustratedembodiments.

Transducer 28 is mounted in pivot mechanism 30 to permit transducer 28to turn around the rotation axis as well as pivot around the pivot axis.In the illustrated embodiments (e.g., FIG. 2), pivot mechanism 30 is atwo-axis gimbal or gimbal-type mounting (or yoke), having a base 50 andmatching arms 56 extending from base 50. Base 50 and arms 56 can beconstructed from a generally cylindrical object having a lumen extendingtherethrough and wherein arms 56 are constructed by cutting out aportion of the cylindrical object. Alternatively, a base 50 and arms 56may be separate pieces which are attached by glue, weld, friction fit,or other suitable means. Base 50 is attached to a bearing 34, so thatpivot mechanism 30 is rotatable about the rotation axis. In someembodiments, bearing 34 has a lumen extending therethrough, whichpermits electrical conductors, guidewires, or other structures to passthrough the bearing. Base 50 includes slots 70, 71, which are cutouts orholes in the wall of base 50. A pivot member 58 is mounted to arms 56via holes 60 in arms 56. Pivot member 58 in the illustrated embodimentis a circular shaped disk having shafts 61 that fit into holes 60 andact as an axle so that pivot member 58 can pivot around the pivot axis.Other gimbal structures could be used which provide pivoting (orelevational) rotational motion to the transducer, examples of which areexplained in U.S. Patent App. Ser. No. 61/713,172 (entitled “Devices andMethods for Three-Dimensional Internal Ultrasound Usage”) and U.S.Patent App. Ser. No. 61/748,774 (entitled “Ultrasound TransducerDirection Control”), which are incorporated herein by reference in theirentirety.

One or more bias members 66 bias pivot member 58 to a particular initialresting or neutral position. In the illustrated embodiment, bias member66 is a torsion spring connected to an arm 56 at or toward one end, andto a shaft 61 or pivot member 58 at the other end (e.g. by inserting anend of bias member 66 into a groove in shaft 61). The torsion spring isa helically shaped spring in a particular embodiment, although otherspring types are suitable. A second bias member 66 (not shown) may besimilarly attached to the other arm 56 and shaft 61 or pivot member 58.In the FIG. 1 embodiment, in the neutral position, transducer 28 isoriented so that transducer 28 has a viewing angle which issubstantially aligned with the rotation axis, e.g. with pivot member 58generally normal to the rotation axis. In other embodiments, the neutralposition can be different (e.g. with the viewing angle substantiallyperpendicular to the rotation axis).

As previously noted, in the illustrated embodiment, transducer 28 ismounted to pivot member 58. Pivot member 58 also includes a magneticlayer 68. Transducer 28 is indicated schematically in the drawings. Theterm “transducer” should be understood to include an assembly of two ormore parts as well as a single piece. It will further be understood that“transducer” as used herein includes devices that transmit ultrasoundsignals (i.e. transform an electrical (RF) signal to ultrasound),receive ultrasound signals (i.e. transform ultrasound to an electrical(RF) signal), or both. If multiple transducers or pieces are provided,transmission of ultrasound may occur at one and reception at another.Transducer(s) as described herein may have one or more piezoelectricelements as respective transducers, and may operate in combination withother transducers within or outside the body. As examples, “transducer”as used herein includes a single element transducer on a rotating andpivoting member or a one-dimensional array of elements on a rotating andpivoting member.

An exemplary transducer 28 includes a body or backing 40 with at leastone ultrasound element 42 attached to one side of backing 40, and one ormore clamping rings. Transducer 28 can include a matching layer (notshown) attached to one side of element 42. Element 42 in this embodimentis a piezoelectric element which has the ability to convert electricalenergy into sound waves and sound waves into electrical energy. Thepositioning of element 42 as indicated, on a side of backing 40, resultsin a directed ultrasound beam direction. Backing 40 may be substantiallyopaque to ultrasound signals, so that such signals are effectively onlyprojected outward from element 42, e.g. to one side or in a limitedangular range radially (relative to the pivot axis) from backing 40. Thematching layer has acoustic impedance generally between that of element42 and the medium surrounding transducer 28 in order to minimizemismatched acoustic impedance between transducer 28 and the mediumsurrounding transducer 28. Transducer 28, as discussed, can be a singleelement transducer which is capable of sending and receiving ultrasoundwaves in a range of frequencies which are typically used in medicalultrasound procedures, such as, for example, in the range from 20 KHz to100 MHz. In some examples, transducer 28 can include a linear array ofelements extending along the rotation axis. Clamping rings have beendetermined to improve efficiency and add mechanical stability totransducer 28.

Magnetic layer 68 is positioned adjacent to or integral with backing 40in the illustrated embodiment. Magnetic layer 68 may be a permanentmagnet attached to transducer 28 adjacent to backing 40. Alternatively,magnetic layer 68 could be incorporated into a transducer housing. Inother embodiments, a magnet or magnetic material may be integrated withthe backing layer as a composite or other method. In the FIG. 1embodiment, magnetic layer 68 is a permanent diametric magnet 69 havinga generally cylindrical shape with the poles aligned in the radialdirection, in which a pole axis running through the north and southpoles is generally perpendicular to the pivot axis.

In particular embodiments, pivot member 58 is a body, base or substrateon which backing 40 of transducer 28 (or transducer 28 itself) is fixed.In other embodiments, backing 40 may include shafts 61 so as to becomethe pivot member in pivot mechanism 30, or a separate axle may beprovided with pivot mechanism 30 to which backing 40 or magnetic layer68 is directly or indirectly fixed. Pivot mechanism 30 permitstransducer 28 to turn around the rotation axis, via bearing 34 anddriving mechanism 32, and to turn transducer 28 about the pivot axis atthe same time, via pulling or pushing force on magnetic layer 68 to moveit around the pivot axis. Pivot member 58 is thus able to rotate aboutboth the pivot axis and the rotation axis simultaneously.

Coil 80 is a conductor which is wrapped or coiled multiple times aboutthe rotation axis. In the embodiment of FIG. 1, coil 80 is positioned inthe axial direction (relative to the rotation axis) on the control sideof transducer 28. Coil 80 is positioned adjacent to wall 24 of catheter22. In some embodiments, coil 80 can be positioned within chamber 26 andpositioned adjacent to or abutting the inside surface of wall 24. Inother embodiments, coil 80 can be positioned adjacent to or abutting theoutside surface of wall 24. In other embodiments, coil 80 can beintegrated into wall 24 of catheter 22. In still other embodiments, coil80 can be positioned about a tubular sheath (not shown) which ispositioned within catheter 22 and surrounds at least a portion of pivotmechanism 30. In this way, catheter 22 or a sheath provide structuralsupport for coil 80. In other embodiments, coil 80 can be positionedcloser to or further from transducer 28. Coil 80 has multiple windingswhich are positioned concentric to the rotation axis. Coil 80 has atleast one end which is connected to a power source (not shown) as by aconductor leading to or toward the operating end of device 20. In someembodiments, coil 80 has two ends which are connected to the powersource by conductors leading to or toward the operating end of device20. In other embodiments, a single conductor conducts a signal towardthe operating end of device 20, and a conductive fluid within chamber 26provides a second conductive path. The power source can be positionedwithin or without catheter 22 (e.g., integrated with the console). Thepower source applies an electric current to coil 80.

In the illustrated embodiment, driving mechanism 32 includes a stop bar100, a driving rod 102, and a friction ring 104. In the illustratedembodiment, stop bar 100 is an elongated elastic bar such as a leafspring constructed of a material (e.g. aluminum, or various polymers)having sufficient elasticity which allows it to flex from a restingposition when impacted and then resume the resting position. Stop bar100 is positioned within the pivotal path of pivot member 58. Stop bar100 is anchored at one or both ends to base 50 (FIG. 3). In the FIG. 3embodiment, end 105 is anchored to base 50 and end 106 is free to movecircumferentially relative to base 50. In one embodiment, end 106 can bepositioned in a cutout or slot within base 50 such that flexing of stopbar 100 causes end 106 to slide within the slot yet maintain arelatively fixed circumferential position relative to base 50. In otherembodiments, both ends 105, 106 may be anchored to base 50. Stop bar 100may include a bumper(s) 101 attached at the center (or substantiallyalong the rotation axis) of stop bar 100. Alternatively, bumper 101 maybe integral to stop bar 100.

Driving rod 102 is an elongated bar attached to stop bar 100. Theattachment may be by glue, weld, friction fit, or other suitable method.Driving rod 102 is constructed of a material which is generally rigid.Driving rod 102 extends perpendicularly from stop bar 100 and has ends107, 108 which extend or are extendable through slots 70, 71 in base 50.Ends 107, 108 are configured to engage friction ring 104. Friction ring104 (or engagement surface) is a circumferential band positionedcircumferentially near base 50. In some embodiments, friction ring 104is the inside surface of wall 24 of catheter 22. In other embodiments,friction ring 104 may include a band of rubber material, or othermaterial which has grooves, slots, or steps positioned at the radiallyinward-most surface of friction ring 104. In some embodiments, frictionring 104 is positioned circumferentially along the inside surface ofwall 24 of catheter 22. In other embodiments, friction ring 104 can bepositioned about a sheath which is separate from wall 24. In stillfurther embodiments, friction ring 104 may include features which aremolded or cut into the inner surface of wall 24. Friction ring 104 ispositioned in the axial direction (relative to the rotation axis)adjacent to driving rod 102 and ends 107, 108.

Coil 80 is positioned such that when energized, coil 80 creates amagnetic field with poles aligned substantially with the rotation axis.In the FIG. 1 embodiment, magnetic layer 68 has poles which aresymmetrically arranged perpendicularly about the pivot axis. A magneticfield produced by coil 80 has a pole (e.g. north) closest to pivotmember 58 which attracts the opposite pole (e.g. south) of magneticlayer 68. The force of attraction between the two poles applies a torqueto pivot member 58. When the torque is large enough to overcome thespring force of bias members 66, pivot member 58 rotates about the pivotaxis from the neutral position. The magnitude of the torque can bevaried by altering the magnitude of the current applied to coil 80, andthe direction of the torque can be changed by reversing the direction ofthe current and thus the polarity of coil 80.

At or near the end of its pivot range, pivot member 58 strikes stop bar100 which is positioned within the pivotal path of pivot member 58. Inthis way, pivot member 58 is free to rotate through a range of about 180degrees, or about 90 degrees in either direction from the neutralposition until a portion of it strikes stop bar 100. Optional bumpers 90are positioned on pivot member 58 adjacent to magnetic layer 68 and arepositioned to engage bumpers 101. In that way, stop bar 100 receiveskinetic energy from pivot member 58 and translates it to driving rod102. The impact from pivot member 58 causes stop bar 100 to flex fromits neutral (or resting) central position. Upon flexing, stop bar 100causes driving rod 102 to move in a longitudinal direction relative todriving rod 102 (or transverse direction relative to stop bar 100). Oneof the ends 107, 108 of driving rod 102 impacts friction ring 104 andthe reactionary force is transferred through stop bar 100 to its anchorpoint(s) on base 50 creating a torque which causes base 50 to rotate aparticular distance (or defined angle) about the rotation axis relativeto friction ring 104 and likewise catheter 22.

The elastic properties of stop bar 100 cause stop bar 100 to return toits neutral position. Similarly, the current applied to coil 80 can bereduced or eliminated so that the spring force of bias members 66overcomes the torque of the magnetic fields in order to return pivotmember 58 to the neutral position. Alternatively or additionally, thecurrent may be reversed to create an opposing magnetic field whichcreates a torque which works in conjunction with the spring force frombias members 66 to return pivot member 58 to or toward the restingposition. Once in the resting position, an opposite (or appropriate)current can be applied to coil 80 which causes pivot member 58 to againrotate about the pivot axis.

It is advantageous for pivot member 58 to alternatingly undergo adriving pivot stroke and a non-driving pivot stroke. The driving pivotstroke has a torque which is larger than the non-driving pivot stroke.The driving pivot stroke has a torque which is large enough to causepivot member 58 to impact stop bar 100 with sufficient force to causedriving rod 102 to impact friction ring 104 and cause rotational motionof pivot mechanism 30 about the rotation axis. The non-driving pivotstroke has a torque which is sufficient to cause pivot member 58 torotate through its complete pivotal range up to and optionally includingimpacting stop bar 100. However, the torque of the non-driving pivotstroke is insufficient to cause driving rod 102 to impact friction ring104. Alternatively, the torque of the non-driving pivot stroke may besufficient to cause driving rod 102 to impact friction ring 104, but thetorque is insufficient to cause rotational motion of pivot mechanism 30about the rotation axis. By continuously providing alternating drivingpivot strokes and non-driving pivot strokes, an incrementalunidirectional rotation of pivot mechanism 30 about the rotation axis isachieved.

Various drive signals can be applied to coil 80 in order to achieve andcontrol the two-axis motion described herein. For example, a drivesignal can include an alternating current applied to coil 80 to achievereciprocating pivotal motion of pivot member 58. The alternating currentrepeatedly changes direction which changes the polarity of the magneticfield produced by coil 80. Correspondingly, the torque applied to pivotmember 58 is alternated repeatedly, and pivot member 58 is caused toreciprocate pivotally about the pivot axis. In this case, the pivotmember strikes the stop bar with the same force at both ends of itspivotal range (FIG. 4), and no continuous unidirectional rotationoccurs. In some embodiments, a direct current (or DC) bias signal isadded to the alternating current signal (illustrated in FIGS. 4-6). TheDC bias signal causes the opposing magnitudes of the AC signal to shiftrelative to a symmetrically centered, neutral axis (FIGS. 5, 6). Thedrive signal then causes a larger torque force (indicated by the boldarrows in FIGS. 5, 6) in one direction relative to the oppositedirection. The larger torque force is transmitted to stop bar 100 at oneend of the pivotal range of pivot member 58 while a smaller torque forceis transmitted to stop bar 100 at the other end of the pivotal range ofpivot member 58. For example, the signal shown in FIG. 5 has a DC signalwhich causes pivot member 58 to strike stop bar 100 with greater forcein a clockwise direction than in the counterclockwise direction.Similarly, the signal shown in FIG. 6 has an opposite DC signal whichcauses pivot member 58 to strike stop bar 100 with greater force in acounterclockwise direction than in the clockwise direction. In this way,the rotational direction of pivot mechanism 30 about the rotation axiscan be controlled and altered by changing and/or reversing a DCcomponent of the drive signal. Other drive signals to accomplish similarresults may be used.

In some instances, device 20 includes a sensor that senses a positionand/or movement of transducer 28, and/or a portion supporting or coupledto transducer 28 (e.g., the pivot mechanism, pivot member 58, ormagnetic layer 68), about the pivot axis (e.g., shaft 61). Similarly,one or more sensors may be included in device 20 to detect therotational position or movement of transducer 28, and/or a portionsupporting or coupled to transducer 28, about the rotation axis (axisA). The sensor outputs sensor data that is communicated to a dataprocessing system (not illustrated) which, in turn, can process thesensor data to calculate the speed (e.g., angular velocity) and/orposition (e.g., angular orientation) of transducer about the pivot axisand/or the rotation axis. The speed and/or position calculation can thenbe paired with the data or signals received from the transducer so as togenerate a graphical image and/or so as to adjust the voltage applied tocoils 80. For example, the data processing system can calculate ormeasure the time between stop bar 100 strikes and, using the knownparameter of the degrees of rotation between strikes, calculate or lookup from a lookup table the rotational speed of the transducer. Thisrotational speed may then be used to determine the position (e.g.,angular orientation) of the transducer at one or more points in time.When the signals received by the transducer are correlated to theposition of the transducer at the time at which that signal wasreceived, a graphical image (e.g., 2D or 3D) may be generated.Alternatively or additionally, the sensor data may be incorporated intoa feedback loop that adjusts the magnitude and/or frequency of the AC orDC signal applied to coil 80. For example, the sensor data may be usedto increase/decrease the voltage and/or frequency of electrical energyapplied to coil 80 so as to increase/decrease the rotational velocity ofthe transducer. Increasing/decreasing the angular velocity (in pivotingand/or rotational movement) of the transducer can be used toincrease/decrease the refresh rate and decrease/increase the resolutionof the graphical image for a given transducer frequency.

The sensor may comprise any sensor suitable for sensing the positionand/or movement of the transducer and/or a portion supporting or coupledto the transducer (e.g., the pivot mechanism, pivot member, or magneticlayer). For example, sensor 110 may comprise a sensor that varies itsoutput in response to the magnetic field of the magnetic layer (e.g., aHall Effect sensor that detects a magnetic pole of magnetic layer 68when the magnetic pole and the sensor are in proximity to one another).As another example, sensor 110 may comprise an electrical contact orswitch that, when contacted by a portion of pivot member 58 such asbumper 90, closes an electrical circuit. Alternatively or additionally,sensor 110 may include an encoder (linear or rotary), a potentiometer,and/or an accelerometer, just to name a few non-limiting examples.

The sensor may be positioned in a number of locations within device 20.In many instances, the position of the sensor will be dependent on thetype of sensor and the position or movement being sensed. For example,one or more Hall Effect sensors may be positioned on arm 56 and/or onbase 50 to sense the position of the magnetic layer about the pivotaxis. In some embodiments, a Hall Effect sensor is positioned underneaththe pivoting transducer on base 50 near the center of the catheter(e.g., close to stop bar 100).

To reduce interference from the magnetic field generated by coil 80, thesensor may be a directional sensor with the direction of sensitivity(indicated by arrows 112) oriented transverse to the magnetic fieldlines created by coil 80. Preferably, the direction of sensitivity ofsensor is orthogonal to the field lines created by coil 80. Forinstance, a Hall Effect sensor can be positioned with the direction ofsensitivity either in a tangential direction to the coil current orextending radially from the center of the loop formed by coil 80 (e.g.,the center of the catheter bore).

As additional examples, an electrical contact sensor can be positionedon stop bar 100, such as on bumper 101, to detect the contact of bumper90 with bumper 101. Additionally or alternatively, a rotary encoder canbe positioned adjacent to shaft 61 to detect rotation about the pivotaxis and/or adjacent to bearing 34 to detect rotation about the rotationaxis. In some instances, the transducer can be used to detect the impactof the pivot member and the stop bar. For example, a transducer havingone or more piezoelectric elements can sense the vibration from when thepivot member strikes the stop bar.

In some embodiments, one or more acoustically opaque or attenuatingfeatures may be placed in the viewing window such that the ultrasoundfield crosses the opaque feature at one or both ends of the pivotingrange of transducer 28. Stop bar 100 may be positioned and/or configuredsuch that transducer 28 stops generally at a moment when the ultrasoundfield crosses the acoustically opaque feature. The acoustically opaquefeature may be added to or integrated with a catheter 22, examples ofwhich are discussed and shown in U.S. Application Ser. No. 61/713,142,entitled “Feedback/Registration Mechanism for Ultrasound Devices,” whichis incorporated by reference herein in its entirety.

Transducer 28 is electronically connected to a power source and to animaging system via signal carriers. Bias members 66 can be constructedof a conductive material and be linked to transducer 28 and/or theconsole or power source to carry electrical signals to and/or fromtransducer 28. In particular embodiments, bias members 66 provide aconduction path from transducer 28 to conductors positioned along arms56. Alternative to or in conjunction with bias members 66, other signalcarriers could be positioned to carry a signal from transducer 28 towardthe console side of device 20. Other examples of signal carriers includeconductors (e.g. wires or cables) along wall 24, through a central lumenof bearing 34, via slip ring connections, and/or via metallic film(s)along wall 24. Examples are discussed and shown in U.S. Application Ser.No. 61/714,275 (entitled “Internal Transducer Assembly with Slip Ring”),which is incorporated by reference herein in its entirety.

A portion of chamber 26 immediately surrounding transducer 28 extendingtowards the application end of catheter 22 can be completely filled witha fluid or other substance having acoustic impedance similar to that ofblood or tissue, such as saline, oils (e.g. mineral oil or castor oil),or mixed alcohol. Sealing member 36 provides a fluid seal between thechamber surrounding transducer 28 and the control side of catheter 22.The substance preferably minimizes friction acting against transducer 28during rotation. Through use of the substance, acoustic matching can beachieved between body fluids, catheter 22, and the medium immediatelysurrounding transducer 28. Acoustic matching ensures that minimal signallosses occur when transmitting and receiving ultrasound signals betweentransducer 28 and body tissue which enhances the clarity of theresulting image. The fluid can be added to device 20 during manufacture,or alternatively could be added prior to use. When the transducer issealed and the coupling fluid is placed into the chamber duringmanufacture, long term contact with the parts necessitates anon-corrosive fluid such as mineral oil or castor oil in order topreserve the shelf life of the product. Preferably, the oil isbio-compatible, acoustically transparent, and has low viscosity.Alternatively, a fluid communication port (not shown) may be positionedor creatable within the catheter or through the catheter wall to allowaccess for adding a fluid. In that case a corrosive fluid may be addedat the time of deployment of device 20. Corrosive fluids such as water,saline, and alcohol typically have more favorable combinations ofbio-compatibility, acoustic transparency and viscosity.

An exemplary use of device 20 will now be given. Device 20 is prepared(e.g. by injecting a fluid into chamber 26, if not already present) andinserted into the body of a patient and maneuvered to a desiredlocation, e.g. in a particular blood vessel. Transducer 28 may beoperated during travel to the desired location, as transducer 28 has aforward neutral position and can be pivoted through use of coil 80.Throughout placement and at a desired imaging location, coil 80 can beenergized in order to pivot transducer 28 about the pivot axis to shiftthe ultrasound field forward and/or laterally. Additionally transducer28 can be rotated about the rotation axis via a driving mechanism 32 toprovide images of tissue(s) or other matter around device 20.Correspondingly, transducer 28 rotates about one or both the rotationaxis and the pivot axis. In this way, device 20 provides an ultrasoundsignal sweep or field that not only turns around the rotation axis ofdevice 20 but also around the pivot axis in order to look forward and/orlaterally of a particular position of transducer 28.

When an ultrasound signal is transmitted, the ultrasound signal passesacross wall 24 of catheter 22 until it encounters an acoustic impedanceboundary (e.g. body tissue, plaque, medical implant, or other materialwhich has acoustic impedance sufficiently different from bodily fluidsor other surrounding material) such that the ultrasound signal is atleast partially reflected at the boundary. At least a portion of theultrasound signal is reflected back towards transducer 28. One or moreelectrical signals representing reflected ultrasound received attransducer 28 are sent from transducer 28 via a conduction pathway tothe ultrasound console, for imaging and/or other data display to thephysician. Simultaneously or subsequently transducer 28 continues totransmit further ultrasound signals and the process is repeated,continuously in certain embodiments over a desired period of time.

An alternative embodiment of driving mechanism 32 is depicted in FIG. 7.In that embodiment, driving mechanism 32 includes a stop bar 200,driving rods 201, 202, 203, 204, and friction ring 104. In theillustrated embodiment, stop bar 200 has a central portion 206. Thedriving rods 201, 202, 203, 204 extend from the central portion 206generally in four separate directions as shown in FIG. 7. The ends ofdriving rods 201, 202, 203, 204 extend through slots or holes in thecircumferential wall of base 50 towards friction ring 104. Centralportion 206 has a hole 208 which is adapted to provide a rotationalmount, wherein stop bar 200 is rotationally mounted relative to base 50substantially along the rotation axis. The mount can be integrated intobearing 34 in a way that provides rotational motion independent ofrotational motion of pivot mechanism 30. Positioned on central portion206 are bumpers 210, 211 which are generally offset from the rotationaxis. Central portion 206 and more specifically bumpers 210, 211 arepositioned within the pivot path of pivot member 58, and bumpers 210,211 are positioned to engage bumpers 90 on pivot member 58 as pivotmember 58 pivots about the pivot axis in this configuration. Bumpers 90can be configured to extend beyond the outer circumferential surface ofpivot member 58 so as to be in a proper position to impact bumpers 210,211 at a position offset from the rotation axis. Alternatively, bumpers210, 211 and/or bumpers 90 can be configured to extend a sufficientdistance away from their respective mounting surfaces so that pivotmember 58 does not physically impede rotation of central portion 206about the rotation axis.

An impact from one of bumpers 90 on one of bumpers 210, 211 causes atorque on central portion 206 which causes central portion 206 to rotateabout hole 208 or the rotation axis (e.g. in a clockwise directionrelative to FIG. 7). Two of the driving rods impact friction ring 104(e.g. driving rods 202, 204) when pivot member 58 strikes stop bar 200.The impact causes one or more of driving rods 201, 202, 203, 204 topartially abut against the edges or inside surfaces of the slots in thewall of base 50. The combination of driving rods impacting friction ring104 and the edges or inside surfaces of the slots in the wall of base 50causes a torque on pivot mechanism 30 which causes it to rotate acertain distance about the rotation axis.

An alternative embodiment of driving mechanism 32 is depicted in FIG. 8.In that embodiment, driving mechanism 32 includes a stop bar 300 andring gear 302. Stop bar 300 includes end 304 and edge 305. Stop bar 300can be integral to base 54 fixedly attached to base 50 at end 304. Stopbar 300 is constructed of a flexible or resilient material (e.g. variousmetals or polymers) that allows edge 305 to flex from a neutral position(or central, or resting) in a generally circumferential direction abouta pivot point which is generally end 304. Edge 305 extends throughopening 306 in base 50. Ring gear 302 is a generally internal gear whichis integrated with or separately attached to wall 24 of catheter 22.Ring gear 302 has inward facing teeth which are configured to engagewith edge 305. Edge 305 is structured as a toothed edge (or knife edge)that engages the inward facing teeth of ring gear 302. Bumpers 308 arepositioned on stop bar 300 in the pivotal path of pivot element 58, andmore specifically in the pivotal path of bumpers 90 on pivot element 58.

During operation (more specifically during a driving pivot stroke) whenpivot member 58 strikes stop bar 300, stop bar 300 receives kineticenergy from pivot member 58 and flexes about end 304. Edge 305 shifts toa point between the next adjacent teeth, and a reactionary force istransferred through stop bar 300 to end 304 and subsequently to base 50causing base 50 to rotate a defined distance (or defined angle) aboutthe rotation axis. During a subsequent non-driving pivot stroke, pivotmember 58 may strike stop bar 300 but the force is insufficient to causeedge 305 to shift to a point between the next adjacent teeth.

A further alternative embodiment is shown in FIG. 9. In this embodiment,pivot mechanism 30 includes arms 56 and base 350. Pivot element 58including transducer 28 is pivotally mounted to arms 56 as previouslydescribed. Base 350 is mounted to bearing 34 (not shown) so that it isrotatable about the rotation axis. Arms 56 and base 350 form a portionof the gimbal-type mounting (or yoke). Lower portions 352 of arms 56connect the application side end of arms 56 to base 350. Lower portions352 are disposed generally radially inward from the application sideends of arms 56. In this embodiment, driving mechanism 32 includes facegear 354, pinion 356 (or external gear), and spur gear 358 (or externalgear). An axle 360 extends between lower portions 352 and isrotationally mounted to lower portions 352 according to a variety ofknown methods. End 362 of axle 360 extends through a hole in one of thelower portions 352. Spur gear 358 is operatively connected to axle 360via end 362 so that spur gear 358 rotates in response to rotation ofaxle 360. In that way, spur gear 358 is rotationally mounted relative tolower portions 352. Pinion 356 is rotationally mounted to one of lowerportions 352 adjacent to spur gear 358. Pinion 356 and spur gear 358 areeach toothed and are positioned so that their respective toothedportions are interengaged. Face gear 354 has a toothed face 364 whichfaces generally in the axial direction relative to the rotation axis.Toothed face 364 is sized and positioned to engage with the toothed faceof pinion 356. Face gear 354 is mounted to the inside surface of wall 24of catheter 22 so that it is fixed relative to catheter 22.Alternatively, face gear 354 can be integrated into or with wall 24.

A tab 366 is mounted to a central portion of axle 360. In thisembodiment, pivot element 58 includes a second tab 368. Tab 368 ispositioned at a circumferential edge of pivot element 58. In theillustrated embodiment, tab 368 is mounted nearest to the magnetic layer68 of pivot element 58. In other embodiments, tab 368 could be mountedcloser to the transducer 28 side of pivot element 58. Tab 366 ispositioned within the pivot path of tab 368 so that tab 368 strikes tab366 when pivot member 58 pivots towards an end of its pivot range. Inother embodiments, tab 366 is positioned within the path of pivot member58 so that pivot member 58 strikes tab 366 when the pivoting.

During operation (more specifically during a driving pivot stroke) whenpivot member 58 causes tab 368 to strike tab 366, tab 366 is caused torotate about the axis of axle 360 and correspondingly axle 360 rotateswhich causes spur gear 358 to rotate an incremental distance. Rotationof spur gear 358 causes pinion 356 to rotate a corresponding incrementaldistance in the opposite rotational direction. Rotation of pinion 356and its engagement with toothed face 364 of face gear 354 causes pinion356 to move circumferentially about the rotation axis along a pathdefined by face gear 354. The movement of pinion 356 applies a torque topivot mechanism 32 which causes pivot mechanism 32 to rotate anincremental distance about the rotation axis.

A spring can be integrated with axle 360 and/or spur gear 358 whichbiases axle 360 and tends to cause tab 366 to return to the upright orneutral position (FIG. 9). Tab 368 is configured to cause tab 366 tomove a sufficient amount for adequate rotation of pivot mechanism 32about the rotation axis while also allowing tab 366 to return to theneutral position after pivot member 58 reaches the end of its pivotingrange and changes its pivoting direction. Driving mechanism 32 caninclude a ratcheting component which prevents spur gear 358 fromadvancing further than a desired incremental distance for eachengagement between tab 366 and tab 368. In some embodiments, theratcheting component includes a small pin with a spring. When tab 368impacts tab 366, the pin is sprung so that it pushes in between gearteeth and prevents excessive rotation, yet sufficient torque on the gearfrom a further impact between tab 368 and tab 366 pushes the pin backout against the spring. The relative sizes of spur gear 358 and pinion356 can be varied in order to achieve a desired incremental rotationaldistance for each impact between tab 368 and tab 366. In that way,specific incremental rotation of pivot mechanism 32 can be achieved.

Controls for the energizing of coil 80 may be provided to maintainrotational and pivotal motion of transducer 28 about the rotation andpivot axes at a particular rotational speed or pattern. Similarly, thevarious embodiments of driving mechanism 32 can be configured to provideparticular angular movements about the rotation axis with each drivingpivot stroke. Examples of configurations can include but are not limitedto varying the flexibility of materials for the stop bars, varying thelengths and sizes of the driving rods, configuring the friction ringswith a variety of friction coefficients, varying the size and shape ofgear teeth, and varying the size and shape of gears. In this way,various rotational and pivotal speed patterns can be achieved. Forexample, a relatively slow spin around the rotation axis (e.g. about 1-2Hz) combined with pivoting around the pivot axis more rapidly, e.g. neara resonant frequency of device 20 can provide good results.

Device 20 facilitates capture of an image through a viewing window whichis free from unnecessary acoustic attenuation such as artifacts,obstructions, or errors within the image. For example, positioning oftransducer 28 at a location which is on an application side of device 20ensures that wires or other echogenic materials are not positionedwithin or across the viewing window of transducer 28, even as transducer28 rotates a complete 360° rotation about the rotation axis as well aspivoting about the pivot axis. In this way, there are no wires or otherreflecting materials which could cause artifacts within the image orblock portions of the redirected ultrasound waves. This provides thephysician a clear view of the entirety of the viewing window. As usedherein, the term “window” includes a substantially obstruction-freepathway throughout the structure of device 20 between transducer 28 andorganic fluids or tissue which may be positioned external to device 20during use.

Device 20 is configured to be used with existing medical devices whichare designed for percutaneous, intraluminal, or interstitial procedures.For example, device 20 can be used as or with a variety of catheters fordifferent purposes, e.g. positioned on or within an application side ofa catheter, depending on the particular configuration. Parts of device20 as previously described can be positioned within an existing lumenwithin the catheter. In an alternative embodiment, device 20 couldinclude an external casing (or sheath) which is similar to catheter 22having walls 24 but being shortened so as to compactly contain device20. Device 20 could be mounted externally to a catheter using a varietyof mounting devices, glues or other types of arrangements. It will beunderstood by those skilled in the art that the particular type ofmounting procedure for the device 20 to an existing medical device caninclude a variety of different types of mounting methods. Accordingly,the particular methods described herein are not indicative of anylimiting aspects of the usage capabilities of the device 20.

While some of the above discussion concerned specific use in the contextof ultrasound system applications, it will be understood thatembodiments of device 20 could also be used for a variety of othermedical procedures and with a variety of other medical devices. Theversatility of the embodiments described herein allows device 20 to beused to guide percutaneous therapeutic interventions such as, forexample, embolism coils, stents, filters, graphs, balloons, biopsies,and ministering therapeutics, etc. Device 20 can be used to locatevarious anatomical landmarks that will be used to correctly place orguided therapy. Typical landmarks include confluences, bifurcations,side branches, nearby vessels, nearby nerves, the heart, and othertissues adjacent to vessels or other orifices containing the transducer.Device 20 can also be used to locate diseased tissue that will betreated or avoided. Device 20 can be used during a biopsy to provide animage of a needle being deployed into tissue. During a TIPS(transjugular intrahepatic portocaval shunt) procedure an image can beproduced to allow a physician to watch a needle being placed into theportal vein. For AAA (aortic abdominal aneurysm) graft delivery, device20 can allow a physician to place a guidewire into a contralateral leg.Device 20 could also be used to image the location of a deployedimplantable device both during and after deployment.

Although particular materials were highlighted herein for somecomponents of the device 20, those materials are not intended to belimiting of the types of materials which are suitable to be used in thedevice 20. Additionally, where materials were not highlighted, a varietyof materials could be used such as certain types of metals, polymers,ceramics or other types of materials which are suitable for use indevices for small body cavity applications.

The device 20 could also be used for a variety of other medicalprocedures and with a variety of other medical devices. It will beunderstood by those skilled in the art that the particular type ofmounting procedure can include a variety of different types of mountingmethods. Accordingly, the particular methods described herein are notindicative of any limiting aspects of the usage capabilities of thedevice 20.

In the use of the terms “rotation” or “rotational,” e.g. with respect toa rotational axis, it should be understood that even though rotationoften implies an angle change much greater than 360°, the devicesdisclosed herein may be configured in certain embodiments so that therotational angle may rotate through angles less than 360°. In someinstances the term “pivot” may be considered by some more natural than“rotate” or vice versa, but for the purposes of this application theterms “rotate” and “pivot” are used for clarity to indicate the axisabout which a change in angle occurs, not the nature or magnitude of theangle change.

While the disclosure has been illustrated and described in detail in thedrawings and foregoing description, the same is to be considered asillustrative and not restrictive in character, it being understood thatonly the preferred embodiments have been shown and described and thatall changes, equivalents, and modifications that come within the spiritof the subject matter defined by following claims are desired to beprotected. It will be understood that features or aspects described orindicated with a particular embodiment or structure may also be usedwith other features, aspects, structures or embodiments. Allpublications, patents, and patent applications cited in thisspecification are herein incorporated by reference as if each individualpublication, patent, or patent application were specifically andindividually indicated to be incorporated by reference and set forth inits entirety herein.

1-21. (canceled)
 22. A medical device for insertion into a body of apatient, comprising: a transducer for transmitting or receiving ortransmitting and receiving ultrasound signals; a pivot mechanismrotatable about a rotation axis; a pivot member mounted to the pivotmechanism and pivotable along a pivot path that extends about a pivotaxis that is substantially perpendicular to the rotation axis; a drivingmechanism positioned within the pivot path of the pivot member, whereinduring rotation about the pivot axis, a portion of the pivot memberstrikes the driving mechanism and causes the pivot mechanism to rotateabout the rotation axis; and a sensor arranged to sense a position ormovement of the pivot member about the pivot axis.
 23. A medical devicefor insertion into a body of a patient, comprising: a transducer fortransmitting or receiving or transmitting and receiving ultrasoundsignals; a pivot mechanism rotatable about a rotation axis; a pivotmember mounted to the pivot mechanism and pivotable along a pivot paththat extends about a pivot axis that is substantially perpendicular tothe rotation axis; a driving mechanism positioned within the pivot pathof the pivot member, wherein during rotation about the pivot axis, aportion of the pivot member strikes the driving mechanism and causes thepivot mechanism to rotate about the rotation axis; and a sensor arrangedto sense a position or movement of the pivot mechanism about therotation axis.
 24. The medical device of claim 22, wherein the medicaldevice is a catheter.
 25. The medical device of claim 22, wherein thesensor is arranged to sense a position or movement of a magnetic layerof the pivot member.
 26. The medical device of claim 25, wherein thesensor includes a Hall Effect sensor.
 27. The medical device of claim22, wherein the sensor includes an electrical switch.
 28. The medicaldevice of claim 22, wherein the sensor includes an encoder.
 29. Themedical device of claim 22, wherein the sensor includes a potentiometer.30. The medical device of claim 22, wherein the sensor includes anaccelerometer.
 31. A system, comprising the medical device of claim 22and a data processing system in communication with the sensor; andwherein the data processing system receives sensor data from the sensorand determines speed or position of the pivot member about the pivotaxis from the sensor data.
 32. The system of claim 31, comprising agraphical display in communication with the data processing system. 33.The system of claim 31, wherein the data processing system is arrangedto control the speed at which the pivot member pivots about the pivotaxis using the sensor data.
 34. The medical device of claim 23, whereinthe medical device is a catheter.
 35. A system, comprising the medicaldevice of claim 23 and a data processing system in communication withthe sensor; and wherein the data processing system receives sensor datafrom the sensor and determines speed or position of the pivot mechanismabout the rotation axis from the sensor data.
 36. The system of claim35, comprising a graphical display in communication with the dataprocessing system.
 37. A catheter, comprising: a transducer fortransmitting or receiving or transmitting and receiving ultrasoundsignals; a pivot mechanism rotatable about a rotation axis; a pivotmember mounted to the pivot mechanism and pivotable along a pivot paththat extends about a pivot axis that is substantially perpendicular tothe rotation axis; and a sensor arranged to sense a position or movementof the pivot member about the pivot axis.
 38. The catheter of claim 37,comprising: an engagement surface positioned cylindrically andconcentric to the rotation axis; a driving mechanism positioned toengage the pivot member and the engagement surface; and wherein thepivot member is pivotable through a range bounded by the drivingmechanism, wherein during pivotal rotation of the pivot member, abutmentof the pivot member against the driving mechanism moves the drivingmechanism to engage the engagement surface to create a reactionary forcewhich causes the pivot mechanism to rotate about the rotation axis. 39.A system, comprising the catheter of claim 37 and a data processingsystem in communication with the sensor; and wherein the data processingsystem receives sensor data from the sensor and determines speed orposition of the pivot member about the pivot axis from the sensor data.40. The system of claim 39, comprising a graphical display incommunication with the data processing system.
 41. The system of claim39, wherein the data processing system is arranged to control the speedat which the pivot member pivots about the pivot axis using the sensordata.